docs: def export_dse_home_in_dse_env_sh(self):
          '''
          Due to the way CCM lays out files, separating the repository
          from the node(s) confs, the `dse-env.sh` script of each node
          needs to have its DSE_HOME var set and exported. Since DSE
          4.5.x, the stock `dse-env.sh` file includes a commented-out
          place to do exactly this, intended for installers.
          Basically: read in the file, write it back out and add the two
          lines.
          'sstableloader' is an example of a node script that depends on
          this, when used in a CCM-built cluster.
          '''
          with open(self.get_bin_dir() + "/dse-env.sh", "r") as dse_env_sh:
              buf = dse_env_sh.readlines()
  
          with open(self.get_bin_dir() + "/dse-env.sh", "w") as out_file:
              for line in buf:
                  out_file.write(line)
                  if line == "# This is here so the installer can force set DSE_HOME\n":
                      out_file.write("DSE_HOME=" + self.get_install_dir() + "\nexport DSE_HOME\n")